System for powering a switch over data communication cabling infrastructure

ABSTRACT

A system for generating, delivering and distributing electrical power to network elements over a data communication network infrastructure within a building, campus or enterprise. Consolidating power distribution and data communications over a single network simplifies and reduces the cost of network element installation and provides a means of supplying uninterrupted or backup power to critical network devices in the event of a power failure. The invention includes power/data combiners that combine a data communication signal with a low frequency power signal. The combined signal is transported over the LAN infrastructure where a power/data splitter extracts the data signal and the power signal and generates two separate outputs. The power over LAN system of the present invention operates with high bandwidth data communication networks, i.e., 10 Mbps, 100 Mbps, 1000 Mbps. The electrical power distributed over the LAN can be delivered as DC or low frequency AC voltages which in either case will not interfere with data communications signals. The electrical power delivered over data communications cable can be transmitted using one or more spare pairs in the cable or over the receive and transmit wires.

REFERENCE TO RELATED APPLICATIONS

This application claims priority from U.S. Provisional Application Ser.No. 60/115,628 filed Jan. 12, 1999.

FIELD OF THE INVENTION

The present invention relates generally to power generation and deliveryand more particularly relates to a system for generating power anddelivering it over the data communication cabling infrastructure withina facility.

BACKGROUND OF THE INVENTION

Currently, the infrastructure making up Ethernet Local Area Networks(LANs) and Wide Area Networks (WANs) is constructed to carry anddistribute high bit rate data communication signals between networkdevices. The network devices or elements, may include, for example,hubs, switches, bridges, routers, interconnection equipment, variousdevices that are equipped with Network Interface Cards (NICs), dataservers, desktop PCs, portable PCs and other various network equipment.What all these devices have in common, among other things, is that theyall require electrical power in order to operate. In each case, theelectrical power consumed by these devices is supplied by internal orexternal batteries or by AC power supplied from a power utility.

Today, every network element device that is not self energized, i.e.,includes an internal or external battery, requires a connection to asource of electrical power in addition to one or more networkconnections. The requirement of network devices to connect to a sourceof electrical power complicates installation and makes it more costly.In addition, it limits the location of network elements to locationswhere electrical power connections and data network connections areavailable. Ultimately, two separate networks must be built andmaintained, wherein each network is connected to the network device. Onenetwork supplies electrical power distribution and the other networksupplies connectivity to the data communications network.

Further, for network devices to operate during partial or completeelectrical power supply interruption or failure, each network devicemust either incorporate an internal battery backup system or must beconnected to an Uninterruptable Power Supply (UPS). Depending on theapplication, such as with IP or LAN telephones, the number of networkdevices that must operate during building power failures may be veryhigh.

Thus, it would be desirable to eliminate the need for each networkdevice that does not operate from a battery to be connected to a sourceof AC utility power, i.e., a standard AC electrical receptacle, inaddition to a network connection. This would significantly reduce thenumber of electrical cables, AC receptacles and associated connectionsthereby simplifying the installation of network devices. In addition,this would also provide a cost effective means for providing anuninterruptable power source to multiple network devices.

It is important to point out that the data communications networkinfrastructure was primarily designed and optimized to carry highbandwidth low power data communications signals and was not designed todeliver electrical power. The IEEE 802.3 standard requires that theelectrical voltages carried over the transmitting cable be isolated andbalanced in reference to earth ground at both ends. Category 3 to 5 LANcables, RJ45 connectors, the line interface of network devices and allIEEE 802.3 compatible devices within the network were not designed tocarry electrical power at a sufficient level to operate the majority ofnetwork devices.

Therefore, any solution that uses the LAN infrastructure tosimultaneously distribute electrical power and provide network datacommunications should address the following points: (1) electrical powerdistribution over the LAN infrastructure should neither increase thenetwork bit error rate (BER) beyond permissible levels nor disturbnormal data communications in any way; (2) electrical power on the LANinfrastructure should not introduce any possibility of harm or risk tousers and network maintenance personnel; (3) electrical power over theLAN infrastructure should not harm or cause damage to standard LANequipment which is not designed to receive power from the datacommunications network; and (4) the addition of electrical power overthe data communications network should not degrade the reliability ofthe network.

Systems for delivering data communication signals over power networksare known in the art. Power line carrier systems are well known andfunction to superimpose relatively high frequency data signals over lowfrequency power cabling. These systems, however, are designed to operateover power lines that are very different from the LAN. The LAN medium isdesigned and constructed to carry data communication signals. Thus, thecables, connectors, line interface circuitry and terminal devices arenot designed to handle high levels of electrical power. This is verydifferent from superimposing low energy level data communication signalsover power line networks.

A block diagram illustrating an example prior art data communicationsnetwork wherein network devices are coupled to the AC main utility poweris shown in FIG. 1. This example network is presented to illustrate thevarious network elements that are typically found in a LAN environment.The network, generally referenced 10, comprises a combination WAN and/orLAN backbone 12 coupled to an IP telephony server 14 and/or to one ormore other service providers 15 and also to a LAN bridge/router 16 whichis connected to a source of AC power via electrical plug 22. The IPtelephony server 14 functions to provide telephone service for aplurality of Internet or IP telephones 52, 36, 28.

The LAN bridge/router 16 is coupled to two LAN hubs or switches 18, 20.IP telephones 28, 36, laptop or other portable computer 32 and desktopcomputer 40 are coupled to LAN hub/switch 18 via network dataconnections 31. LAN hub/switch 18 is connected to a separate source ofAC power via electrical plug 24. IP telephone 28, 36, portable computer32 and desktop computer 40 are connected to a source of AC power viaelectrical plugs 30, 38, 34, 42, respectively.

The LAN hub/switch 20 is also coupled to a separate source of AC powervia electrical plug 26. A video camera 44 (e.g., standard video cameraor Web camera), portable computer 48 and IP telephone 52 are coupled toLAN hub/switch 20 via network data only connections 47. Video camera 44,portable computer 48 and IP telephone 52 are connected to a source of ACpower via electrical plugs 46, 50, 54, respectively.

It is noted that each network device requires a separate datacommunications connection and a connection to a source of electricalpower. The data networking connection is made in the normal manner usingstandard LAN cabling to conventional hubs, switches, routers, etc.Electrical power to each network device is supplied via a plurality ofAC mains receptacles. Thus, each network device must be provided with atleast two utility hook ups: one to the data communications network andthe second to the AC electrical power network.

SUMMARY OF THE INVENTION

The present invention is a system for generating, delivering anddistributing electrical power to network elements over a datacommunication network infrastructure within a building, campus orenterprise. Consolidating power distribution and data communicationsover a single network serves to (1) both simplify and reduce the cost ofnetwork element installation and (2) provide a means of supplyinguninterrupted or backup power to critical network devices in the eventof a power failure.

Network installations that utilize the present invention can besimplified and are less costly because the number of required powercables, power receptacles and AC power supplies or adapters is greatlyreduced. In addition, network devices, terminals and other networkingequipment can be placed without regard to the existence of or thelocation of AC receptacles.

The system of the present invention also provides for a significant costreduction in providing uninterruptable backup electrical power tocritical network devices and terminals in the event of a power supplyfailure or interruption. This is due to the fact that distributingbackup power, i.e., power from an uninterruptable power supply, from afew points in the network via the LAN infrastructure is far moreefficient than connecting each critical network element to its owndedicated UPS or to a backed up power line. An assumption that is validmost of the time is that only a relatively small portion of the networkelements, e.g., hubs, switches, routers, etc., need to be connected to adedicated source of uninterruptable power while the remainder of thecritical network devices receive their operating power via the LANinfrastructure.

Another benefit of the system of the present invention is that thesafety requirements and cost of network terminal equipment can bereduced since electrical power can now be fed from low voltagesdelivered over the LAN infrastructure. This is in contrast to thecurrent method of providing an internal or external 110/220 VAC powersupply that requires that the network device receive certification byone or more testing organizations such as Underwriters Laboratory (UL).In the case of IP telephony, which is becoming more and more popular,providing power over the LAN permits the IP telephone to have a sourceof uninterruptable power just as ordinary analog based telephonesconnected to the PSTN enjoy today.

The disclosure presented hereinbelow describes an apparatus for andmethods for generating, delivering and managing electrical power overLAN network infrastructures that are primarily designed for digitalcommunications purposes. The invention functions to reduce any possibledisturbances to the data communications and to maintain compatibilitywith the IEEE 802.3 and other relevant standards.

The power over LAN system of the present invention operates with highbandwidth data communication networks, i.e., 10 Mbps, 100 Mbps, 1000Mbps, which are naturally more susceptible to noise, network bandwidth,near end and alien crosstalk. In addition, the present invention takesinto account the limitation in cable length imposed by modern LANs,i.e., hundreds of meters versus kilometers in PSTN, ISDN and HDSLcommunication lines. The invention discloses novel remote power feedingmethods that are better suited for shorter haul cable runs.

Further, the electrical power distributed over the LAN can be deliveredas DC or low frequency AC voltages which in either case will interfereminimally with data communications signals. The electrical powerdelivered over the data communications cable can be transmitted usingone or more spare pairs in the cable. Ethernet communications requires 2pairs (4 conductors) to implement. If 4 pair (8 conductor) Category 3, 4or 5 cable is used, than 2 pairs are not used for data communications.The electrical power can be transmitted using one or more of the cablewire pairs. Alternatively, if the data cable comprises only two pair,then the electrical power is distributed using one or two of theavailable pairs, i.e., the receive and transmit wires. Thus, inaccordance with the invention, power can be delivered over anycombination of used and/or unused twisted pair wires in the datacommunication cable.

There is provided in accordance with the present invention a system fordistributing electrical power over a data communication cablinginfrastructure to one or more electrical power consuming network devicescomprising a data communications cabling network, a source of electricalpower, at least one power/data combiner coupled to the source ofelectrical power and to the data communications cabling network, the atleast one power/data combiner operative to generate and inject a lowfrequency power signal onto a data communications signal received fromthe data communications cabling network so as to yield a combinedpower/data signal which is subsequently output onto the datacommunications cabling network and at least one power/data splitteradapted to receive the combined power/data signal and to extract andseparate therefrom the original data communication signal and the lowfrequency power signal.

The data communications network may comprise an Ethernet based LocalArea Network (LAN). The power/data combiner can be implemented as astandalone unit, integrated into a Local Area Network (LAN) hub or intoa Local Area Network (LAN) switch.

The power/data combiner may comprise a plurality of data only inputports and a plurality of data plus power output ports, each data in portand data plus power output port forming a separate channel. In addition,the power/data combiner is adapted to receive electrical from an ACmains power receptacle, an uninterruptable Power Supply (UPS) or ananother power/data combiner.

The power/data combiner comprises means for filtering high frequencynoise and ripple, for sensing the current in the low frequency powersignal, for connecting and disconnecting the low frequency power signalto and from the combined output power/data signal and for detectingno-load and overload conditions on the combined output power/datasignal.

The system further comprises a management unit for monitoring andprovisioning, via the data communications cabling network, thepower/data combiners and power/data splitters located in the datacommunications cabling network.

The power/data splitter can be implemented as a standalone unit orintegrated into a network device. The power/data combiner may comprisean AC/DC or DC/DC power converter for converting the extracted lowfrequency power signal into one or more output voltages.

There is also provided in accordance with the present invention a methodfor distributing electrical power over a data communication cablinginfrastructure to one or more electrical power consuming networkdevices, the method comprising the steps of generating a low frequencypower signal from a source of electrical power, injecting the lowfrequency power signal into a data communications signal being carriedover the data communications cabling network so as to generate acombined power/data signal, transmitting the combined power/data signalonto the data communications cabling network, receiving the combinedpower/data signal carried over the data communication cabling networkand splitting the combined power/data signal so as to yield the datacommunication signal separated from the low frequency power signal.

There is further provided in accordance with the present invention asystem for distributing electrical power over a data communicationcabling infrastructure to one or more electrical power consuming networkdevices comprising a data communications cabling network, a source ofelectrical power, power supply means for generating a low frequencypower signal from the source of electrical power, combiner means coupledto the data communications cabling network, the combiner means forinjecting the low frequency power signal onto a data communicationssignal being carried over the data communications cabling network so asto yield a combined power/data signal, regulator means for regulatingthe injection of the low frequency power signal onto the datacommunications signal, the regulation including, but not limited to,ceasing the injection of the low frequency power signal and limiting itscurrent, extraction means for extracting the low frequency power signalfrom the combined power/data signal and for outputting the original datacommunication signal and the low frequency power signal.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is herein described, by way of example only, withreference to the accompanying drawings, wherein:

The invention is herein described, by way of example only, withreference to the accompanying drawings, wherein:

FIG. 1 is a block diagram illustrating an example prior art datacommunications network wherein network devices are coupled to the ACmain utility power;

FIGS. 2A and 2B are a block diagram illustrating an example datacommunications system constructed in accordance with the presentinvention wherein network devices receive electrical and networkconnectivity over the same cable;

FIG. 3 is a block diagram illustrating a power/data combiner unit forplacing electrical power onto the data communications infrastructure;and

FIG. 4 is a block diagram illustrating a power/data splitter unit forseparating electrical power form the data communications infrastructure.

DETAILED DESCRIPTION OF THE INVENTION Notation Used Throughout

The following notation is used throughout this document. Term DefinitionAC Alternating Current BER Bit Error Rate DC Direct Current HDSL Highbit rate Digital Subscriber Loop IP Internet Protocol ISDN IntegratedService Digital Network LAN Local Area Network NIC Network InterfaceCard PC Personal Computer PSTN Public Switched Telephone Network ULUnderwriters Laboratory UPS Uninterruptable Power Supply WAN Wide AreaNetwork

General Description

The present invention is a system for generating, delivering anddistributing electrical power to network elements over a datacommunication network infrastructure within a building, campus orenterprise. Consolidating power distribution and data communicationsover a single network serves to simplify and reduce the cost of networkelement installation and to provide a means of supplying uninterruptedor backup electrical power to critical network devices in the event of apower failure.

The disclosure presented hereinbelow describes an apparatus for andmethods for generating, delivering and managing electrical power overLAN network infrastructure that is primarily designed for digitalcommunications purposes. The invention functions to reduce any possibledisturbances to the data communications and to maintain compatibilitywith the IEEE 802.3 and other relevant standards.

A block diagram illustrating an example data communications systemconstructed in accordance with the present invention wherein networkdevices receive electrical and network connectivity over the same cableis shown in FIGS. 2A and 2B. The network, generally referenced 60,comprises a WAN and/or LAN backbone 64 that is coupled to an IPtelephone server 62, other service providers 61, a power over LANmanagement unit 164 and a LAN bridge/router 66. The IP telephony server62 serves to provide telephone service to the plurality of IP telephonesconnected to the network 60. The power over LAN management unit 164,described in more detail hereinbelow, provides administrative and powermanagement functions for all the power over LAN enabled devices in thenetwork.

Electrical power may be combined with the data communication signals ina device termed a power/data combiner. The combined power/data signal istransmitted over standard LAN cabling, e.g., Category 3, 4, 5 LANcabling, which meets EIA/TIA 568A or similar premises cabling standard,a network device that functions to split or separate the data from thepower. The data signal is input to the network port on the device andthe electrical power is input to the power input connector on thedevice.

In one embodiment, the power/data combiner circuitry is implemented as astandalone external power/data combiner unit 168. Alternatively, it isimplemented together with a network element such as a hub or switch andreferred to as an integrated power/data combiner hub/switch 72, 90.

Similarly, in one embodiment, the power/data splitter is implemented asa standalone external power/data splitter unit 156. Alternatively, it isintegrated into a network device such as IP telephone 102.

Whether or not the power/data combiner and power/data splitter areimplemented as an external standalone unit or integrated into a networkdevice, their functionality is similar. The power/data combinerfunctions to superimpose a low frequency power signal onto the highfrequency, low power data communications signal. The low frequency powersignal may have a frequency, for example, from DC up to conventionalpower utility frequencies, i.e., 50 or 60 Hz. The power/data splitterfunctions to separate the low frequency power signal from the highfrequency, low power data communication signal.

Various alternative embodiments of the power over LAN system of thepresent invention are shown in FIGS. 2A and 2B. Not all the networkelements are power over LAN enabled. Not all the devices must be powerover LAN enabled. Conventional non power over LAN network devices canexist in the same network. The power over LAN enabled devices operatetransparently from non enabled devices.

Typical applications of network systems/elements that the power over LANsystem of the present invention can be applied to include, but are notlimited to, in general, any system or element that is connected to aLAN, and more specifically, IP or LAN telephony, digital video cameras,Web cameras, video conferencing equipment, wireless LAN productsincorporating transmitters and receivers, portable computers,workstations and network printers. Also included are security systemdevices such as alarms and sensors that are connected to the network,remotely controlled Smart Home devices such as LonWorks or CEBuscompatible products and all types of traditional data networkingequipment such as hubs, switches, routers, bridges. Each of the abovelisted devices can be adapted to receive their operating electricalpower from the LAN infrastructure. The number and type of devices thatcan be adapted to receive power over the LAN is limited, however, to theamount of power the LAN cabling is able to carry in terms of safety andcost.

The power over LAN system comprises systems and subsystems that can beintegrated together at any network level, i.e., from the networkelement/device level through the network hub and backbone switch level.The power over LAN system can be added onto a conventional LANinstallation or can be integrated into the network elements themselves,e.g., hubs, switches, routers, bridges, switches, etc.

Some of the devices receive electrical power from the AC mainreceptacles and some receive power over the LAN cabling infrastructure.The LAN bridge/router 66 receives AC main power via electrical plug 68.Likewise integrated power/data combiner hub/switch 72 and conventionalLAN hub/switch 106, 128, receive AC main power via electrical plugs 74,108, 130, respectively. External power/data combiner unit 168 receivespower from UPS 171 which, in turn, is connected to AC main power viaelectrical plug 170. Integrated power/data combiner hub/switch 90receives power over the LAN cabling via cable 88.

Integrated power/data combiner hub/switch 72 is connected to the LANbridge/router 66 via a cable 70 that carries only data. Network devicesconnected to the hub/switch 72 include IP telephones 76, 80. IPtelephone 76 is connected by a combined power/data cable 86 andintegrates a power/data splitter within the phone. IP telephone 80 isconnected to an external power/data splitter 78 via separate data cable82 and power cable 84. The power/data splitter 78 is connected to thehub/switch 72 via a cable 77 that carries both power and data.

Devices coupled to the integrated power/data combiner hub/switch 90include portable computer 96 and IP telephone 102. The portable computer96 is connected to an external power/data splitter 94 via a cable 100that carries only data and a power cable 98. The power/data splitter 94is connected to the hub/switch 90 via a cable 92 that carries both powerand data. IP telephone 102 is connected by a cable 104 that carries bothpower and data and integrates a power/data splitter within the phone.Note that the hub/switch 90 comprises an internal power/data splitter toseparate the combined data communications signal and electrical powersignal received from hub/switch 72.

Conventional LAN hub/switch 106 is connected to the bridge/router 66 andto AC power via electrical plug 108. Network devices connected to thehub/switch 106 include IP telephone 112 and desktop computers 118, 124.The IP telephone is connected to the hub/switch 106 via a cable 110 thatcarries only data and to AC power via electrical plug 114. Desktopcomputers 118, 124 are connected to the hub/switch-106 via data onlycables 116, 122, respectively, and to AC power via electrical plugs 120,126, respectively.

A data communications only cable 132 connects the bridge/router 66 tothe external power/data combiner unit 168. A data communications onlycable 166 connects the power/data combiner unit 168 to a conventionalLAN hub/switch 128 that is connected to AC power via electrical plug130. The power/data combiner unit 168 is connected to a plurality ofnetwork devices comprising a network ready video camera 136, IPtelephone 142, 158 and desktop computer 150. Each network deviceconnected to the power/data combiner unit 168 has a corresponding datacommunications only connection from the power/data combiner unit 168 tothe hub/switch 128. Under normal operating conditions, thecommunications signals received over data cable 132 are passed through,i.e., bridged, transparently to data cable 166. In the event of a powerfailure, however, the conventional LAN hub/switch 128 is bypassed andthe data communication signals are routed directly to the networkdevices connected to the power/data combiner unit 168.

The network ready video camera 136 is connected to the power/datacombiner 168 via a cable 138 that carries both data and power. IPtelephone 142 is connected to an external power/data splitter 140 viaseparate data cable 144 and power cable 146. The power/data splitter 140is connected to the power/data combiner unit 168 via a combinedpower/data cable 148. Similarly, IP telephone 158 is connected to anexternal power/data splitter 156 via separate data cable 162 and powercable 160. The power/data splitter 156 is connected to the power/datacombiner unit 168 via a combined power/data cable 154. Desktop computer150 is connected to the power/data combiner unit 168 via a datacommunications only cable 152 and to AC power via electrical plug 172.

As described above, the network 60 can be adapted to provide backupelectrical power in the event of a power failure. One or more UPS unitscan be placed strategically in the network 60 to provide power tocritical network devices that must be powered even in the event of apower failure. Examples include IP telephones, networked securitydevices, wireless LAN devices incorporating transmitters and receivers,etc. In the example network shown in FIGS. 2A and 2B, the UPS unit 171is connected to AC power via electrical plug 170 and provides power toexternal power/data combiner unit 168. Alternatively, additional UPSunits can be placed in the network and/or UPS 171 can be adapted tosupply electrical power to more than one power/data combiner device.

It is important to note that distributing backup electrical power, i.e.,power from an uninterruptable power source, from a few points in thenetwork via the LAN infrastructure is more cost effective thanconnecting each critical network element to its own dedicated UPS oralternatively creating a UPS power distribution cabling systemthroughout the organization in addition to the ordinary power network.In the event of a power failure, electrical power is supplied from theUPS to those critical network elements that require it. Which power overLAN enabled network devices are to receive power in the event of afailure can be configured into the power/data combiner unit beforehand.Configuration can be performed locally via a management port or remotelyvia the management unit 164 connected to the LAN/WAN backbone 64.

It is important to note that a benefit of the system of the presentinvention is that the safety requirements and cost of network terminalequipment can be reduced since electrical power is distributed as lowvoltages over the LAN infrastructure. In the case of IP telephonyproviding power over the LAN permits the IP telephone to have a sourceof uninterruptable power just as ordinary analog based telephonesconnected to the PSTN enjoy today.

The electrical power distributed over the LAN can be delivered either asDC or low frequency AC voltages. In either case, the delivery of powerover the LAN infrastructure does not interfere with data communicationssignals. The power voltages over the LAN cabling are kept below 120 Vpeak and the current is limited in order to maintain compatibility withsafety standards such as UL 60950 and EN 60950.

Note also that the electrical power delivered over LAN cabling can betransmitted using one or more spare pairs in the cable. Ethernetcommunications requires 2 pairs (4 conductors) to implement. If thecabling plant is EIA/TIA 568A compatible and includes 4 pairs, than 2pairs remain unused. The electrical power can be transmitted using oneor two of the unused pairs. In this case the power splitter and combinerare not necessarily needed and direct injection and extraction of powercan be implemented. Alternatively, if the data cable comprises only twopair, then the electrical power is distributed using one or two of theavailable pairs, i.e., the receive and transmit wires.

Power/Data Combiner Unit

A block diagram illustrating a power/data combiner unit for placingelectrical power onto the data communications infrastructure is shown inFIG. 3. As described previously, the power/data combiner functions,whether implemented as an external stand alone unit or integrated with anetwork element, functions to combine an electrical power signal and adata communications signal to form a combined power/data signal. Thedescription that follows uses the external power/data combiner as anillustrative example. Note, however, that the description applies aswell to the integrated embodiment.

The power/data combiner, generally referenced 180, comprises lineinterface circuitry 181, filtering and protection circuitry 182, a powersupply 184 and a controller 186. The line interface circuitry 181comprises a plurality of input ports 190 and output ports 188 andprovided voltage isolation between all inputs and outputs. The inputports 190 receive data only signals from a hub or switch. The outputports 188 output a combined data plus power signal to connected powerover LAN enabled devices, e.g., power/data splitters or integratednetwork elements.

The power/data combiner unit 180 is connected to a conventional LAN10/100/1000 Base T hub or switch via the data in ports 190. Note thatalthough eight data in ports are shown, the power/data combiner cancomprise any number of data in ports, e.g., 16, 24, 32. The conventionalhub or switch and power/data combiner 180 may or may not have the samenumber of ports, but preferably they are the same. The power/datacombiner unit 180 functions to inject the DC or AC power to each LANchannel.

The power/data combiner unit 180 is adapted to accept electrical powerfrom ordinary building AC power, an UPS or from another power over LANenabled device and to distribute it to one or more network deviceconnected thereto. Each output channel may comprise an Ethernet channelthat carries data communications signals only, power signals only orboth data communications and power signals simultaneously. Thepower/data combiner unit comprises circuitry that minimizes anydisturbances to data communications.

The power supply 184 is connected to a source of AC electrical power viaconnector or cable 192. Alternatively, the power can be received fromanother power/data combiner unit. The power supply 184 functions toprovide the energy needed for the operation of the power/data combinerunit 180 itself and the total energy needed by the remotely powerednetwork devices connected downstream of the unit 180. The power supply184 is preferably constructed to support the worst case energy, i.e.,maximum, required by a channel multiplied by the number of channels.Alternatively, the power supply 184 is constructed to support a lesseramount of power assuming there exists an a priori prediction of powerconsumption by all channels.

The filter and protection circuit 182 functions to permit the highfrequency data communications signal to pass uninterrupted andtransparently from input to output. The circuit 182 prevents the lowimpedance output of the power supply from attenuating the datacommunications signal and prevents communications signals on one channelfrom leaking into another channel via the common power supply unit 184,i.e., prevents crosstalk. The circuit also functions to filter the highfrequency ripple and noise produced by switching power supplies and toprovide a high output impedance from the power supply for highfrequencies.

Further functions of the filter and protection circuit 182 compriselimiting the power available to each channel in accordance with apredetermined level, current sensing for each wire pair, minimum andmaximum current threshold reference levels, unbalanced or currentleakage detection and the capability of connecting and disconnectingpower to/from each channel. The minimum and maximum current thresholdreference levels may be fixed or controlled via a management unitdepending on the implementation and configuration of the system. Animportant function of the circuit 182 is that it will disconnect ashorted or otherwise faulty port such that other operational channelsare not effected.

The controller 186, suitably programmed, functions to administer andcontrol the operation of the components within the power/data combiner180 and to provide telemetry functions to an external management entity.The controller functions to communicate with a management unit connectedeither locally or remotely via the network. The controller permitsonline modification of the power being distributed to each channel.Other functions include status reporting such as reporting on the powerconsumed by each channel, any channel failures and any failures withinthe power/data combiner unit itself.

In the integrated embodiment, the power/data combiner unit functionalityis integrated into a conventional LAN connectivity hub or switch, e.g.,10, 100 or 1000 BaseT. The internal power supply of the hub is modifiedto support the increased load of the normal hub operation and the remotepower feeding functions. A line interface circuit is inserted betweenthe output port and the internal networking circuitry of the hub. Inaddition, the filtering and protection circuitry is added to couple theline interface circuitry to the power supply. Each of the standard LANports is replaced with a combined data plus power port. This integratedembodiment serves to reduce overall system cost, reduce the spacerequired and reduces the complexity of the network. It does require,however, modification of a conventional hub or switch.

In either the external or integrated embodiments, the data beingreceived by the power/data combiner is bidirectional transferred fromeach channel input to its corresponding channel output. The power isinjected into each channel output port. The amount of output powerallotted to each output channel can be set independently. In addition,each output channel is self protected against short circuit and overloadconditions.

Further, in connection with the external power/data combiner embodiment,two additional LAN ports can optionally be provided. An input LAN portand an output LAN port can be provided whereby during normal operation,the two ports are bridged together. The conventional hub or switch isfed via the output LAN output port. The input LAN port is connected tothe upstream network device, e.g., hub or switch. In the event of apower failure, the power/data combiner unit disconnects the input andoutput LAN ports and directs the data communications from the input LANport directly to one or more output channels. Thus, both data and powercontinuity are provided in the event the upstream data hub or switch isnot operational.

Power/Data Splitter Unit

A block diagram illustrating a power/data splitter unit for separatingelectrical power form the data communications infrastructure is shown inFIG. 4. As described previously, the power/data splitter functions toaccept a LAN channel at its input that carries both power and datasimultaneously over the same cable wires and to separate the two signalsinto a power signal and a data signal. Both these signals are thenforwarded to the attached network device. The two output signals cancomprise two separate cable connections, i.e., one for data and one forpower. The data cable connection behaves as a standard LAN data channeldedicated for data communications. The power cable connection serves todrive the power loads with power extracted from the combined input. Thepower/data splitter functions to isolate the input voltage from theoutput voltage. In addition, an AC/DC or DC/DC voltage converter can beused to convert the input voltage to one or more voltage levels to meetthe specific requirements of the attached network device.

The power/data splitter, generally referenced 200, comprises lineinterface circuitry 202, filtering and protection circuitry 206, a powerconverter 208 and a controller 204. The splitter 200 is normallyconnected between the LAN wall outlet receptacle, for example, and thenetwork device. Functionally, the power/data splitter 200 blocks highfrequency signals from passing through to the power output by presentinga high impedance to high frequencies, allows low frequency and DC powersignals to pass through and blocks conduction of high frequency noisefrom the power converter input to the data channel.

The line interface circuitry 202 comprises a data plus power input port210 and a data communications only output port 212. The extracted poweris output via power output port 214. The line interface circuitry 202receives the signal from a LAN channel and provides high pass filteringto permit undisturbed bidirectional transport of the data communicationsignal form the data plus power input port 210 to the data only outputport 212.

The filtering and protection circuitry 206 provides low pass filteringbetween the data plus power input port 210 to the input of the powerconverter 208. The power converter 208 accepts the voltage extractedfrom the LAN channel and functions to convert it to one or more outputvoltages. The power converter 208 may comprise an AC/DC or a DC/DCvoltage converter depending on the voltage extracted from the LANchannel. The power converter can be adapted to generate any number ofvoltages in accordance with the specific requirements of the networkdevice attached to the power/data splitter 200.

The controller 204, suitably programmed, functions to administer andcontrol the operation of the components within the power/data splitter200 and to provide telemetry functions to an external management entity.The controller functions to communicate with a management unit connectedeither locally or remotely via the network. Other optional functionsinclude status reporting such as reporting on the power consumed by eachchannel, any channel failures and any failures within the power/datasplitter itself.

In the integrated embodiment, the power/data splitter functionality isintegrated into a conventional network device, e.g., IP or LANtelephone, portable or desktop computer. The network device is modifiedto receive the combined power/data signal. The standard LAN port andpower port are replaced with a combined data plus power port. A lineinterface circuit is inserted between the input port and the internalnetwork data and power in port. In addition, the filtering andprotection circuitry is added to couple the line interface circuitry tothe power supply. This integrated embodiment serves to reduce overallsystem cost, reduce the space required and reduces the complexity of thenetwork. It requires, however, modification of a conventional networkdevice.

Power Over LAN Management Unit

It would be inefficient in terms of complexity and cost to construct apower delivery and distribution network assuming that each network portand node simultaneously consumes the maximum allocated output power. Inaddition, such a power network would likely create power ‘bottlenecks’over the data network and would force the use of special cabling that isnon standard for common LAN installations. Further, the equipment usedto implement such a power network would most likely exceed the thermaland power specifications of standard networking equipment cabinets whichare designed to hold stackable hubs, switches, routers and various typesof network management units, resulting in a failure to accommodate suchequipment.

Therefore, the power over LAN system of the present invention mayutilize in the construction of the power network, the statisticalpatterns that indicate the expected power consumption during (1) normalnetwork operation and during (2) emergency operation in the event of abuilding power failure.

The management unit 164 (FIG. 2A) comprises software that may execute onany PC or server connected to the network. The management unit functionsto communicate telemetry and control information to the power over LANcomponents, e.g., power/data combiners and splitters, distributedthroughout the network. The data communications network itselftransports the data messages between the power over LAN enabled devicesand the management unit. The management unit provides monitoring andprovisioning functions. The provisioning function allocates theavailable power resources, in an analogous manner to network datatraffic being managed, and serves to configure the power path across thenetwork from source to sink.

A network administrator is able to determine the systems method forhandling those network ports that indicate no-load, overload or currentleakage to earth ground. The power to a faulty port can be shut down orlimited to a desired value. Recovery from a shut down state can beautomatic based on port condition or can be done manually. Each port canbe configured individually in accordance with system setupconfiguration.

Note that each power/data combiner can be constructed to be managedindependently or via external control. Each power/data combiner maycomprise a dedicated LAN data connection or it may compriseserial/parallel communications to a network host system that, in turn,transfers telemetry and control data to the network LAN.

Reduced Power Operation

In the event of a building power failure, certain network devices andnodes, e.g., hubs, routers, bridges, switches, etc., may need to bebypassed in order to maintain data and power continuity between criticalnetwork nodes, terminals and devices. The electrical power that issupplied by a single large LAN channel should, in most cases, besufficient to operate the majority of network devices. This LAN channel,however, probably would not be sufficient to simultaneously operate anormal network hub/switch and all of its connected network devices. Inaddition, LAN devices are typically useless unless they receive bothpower and data communications at the same time. The power over LANsystem of the present invention functions to maintain the flow ofelectrical power and data communications in the event of a failure. TheLAN node units, i.e., hubs, switches, etc., and network devices switchto a reduced power operating mode during building power failures. When adevice is in a reduced power operating mode, it will either reduce itsdata handling bandwidth and/or processing activities and keep only a fewports active and shut down its remaining ports in order to reduce itsoverall power consumption. Thus, a battery based UPS can be used tosupport a plurality of critical network elements for extended periods oftime.

While the invention has been described with respect to a limited numberof embodiments, it will be appreciated that many variations,modifications and other applications of the invention may be made.

1-37. (canceled)
 38. A local area network comprising: a first pluralityof local area network nodes; a first power data combiner; firstcommunication cabling connecting said first plurality of local areanetwork nodes to said first power data combiner for providing datacommunication; a second power data combiner; and second communicationcabling connecting said first power data combiner to said second powerdata combiner, said second power data combiner providing current limitedpower to said first power data combiner via said second communicationcabling, said first power data combiner comprising: line interfacecircuitry coupling at least some of said power provided via said secondcommunication cabling into said first communication cablingsubstantially without interfering with data communication; and currentlimiting circuitry connected to said line interface circuitry andcontrolling current delivered by said line interface circuitry into saidfirst communication cabling, wherein said first power data combiner isoperative to provide at least said plurality of first local area networknodes via said first communication cabling, said current limitingcircuitry being operative to provide a current limit level for each ofsaid first plurality of local area network nodes.
 39. A local areanetwork according to claim 38, wherein said second power data combinerprovides said current limited power to said first power data combinervia said second communication cabling utilizing a combined power datasignal.
 40. A local area network according to claim 38, furthercomprising: a second plurality of local area network nodes; and thirdcommunication cabling connecting said second plurality of local areanetwork nodes to said second power data combiner; said second power datacombiner being operative to provide power to at least one of said secondplurality of local area network nodes via said third communicationcabling.
 41. A local area network according to claim 38, furthercomprising: a second plurality of local area network nodes; and thirdcommunication cabling connecting said second plurality of local areanetwork nodes to said second power data combiner, said second power datacombiner comprising current limiting circuitry and being operative toprovide power to at least one of said second plurality of local areanetwork nodes via said third communication cabling, said currentlimiting circuitry of said second power combiner being operative toprovide a current limit for each of said second plurality of local areanetwork nodes being provided power via said third communication cabling.42. A local area network according to claim 41, wherein said currentlimiting circuitry of said second power combiner is further operative toprovide a current limit for said provided current limited power to saidfirst power data combiner.
 43. A local area network according to claim38, wherein at least one of said first power data combiner and saidsecond power data combiner is integrated with one of a hub and a switch.44. A local area network comprising: a first plurality of local areanetwork nodes; a switch assembly; a power data combiner; firstcommunication cabling connecting said first plurality of local areanetwork nodes to said first switch assembly for providing datacommunication; and second communication cabling connecting said switchassembly to said power data combiner for providing data communication,said power data combiner being operative to provide power to said switchassembly via said second communication cabling; said switch assemblycomprising: first line interface circuitry being operative to couple atleast some of said provided power into said first communication cablingsubstantially without interfering with data communication; and firstcurrent limiting circuitry connected to said first line interfacecircuitry and being operative to control current delivered by said lineinterface circuitry into said first communication cabling, wherein saidswitch assembly is operative to provide at least some of said powerprovided from said power data combiner to at least some of said firstplurality of local area network nodes via said first communicationcabling, said first current limiting circuitry being operative toprovide a current limit level for each of said powered nodes of saidfirst plurality of local area network nodes.
 45. A local area networkaccording to claim 44, wherein said power data combiner comprises:second line interface circuitry coupling power into said secondcommunication cabling substantially without interfering with datacommunication; and second current limiting circuitry connected to saidsecond line interface circuitry and controlling current delivered bysaid second line interface circuitry into said second communicationcabling, said second current limiting circuitry being operative toprovide a current limit for said power provided to said switch assembly.46. A local area network according to claim 45, further comprising: asecond plurality of local area network nodes; and third communicationcabling connecting said second plurality of local area network nodes tosaid power data combiner, said power data combiner being furtheroperative to provide power via said third communication cabling to atleast one of said second plurality of local area network nodes.
 47. Alocal area network according to claim 45, further comprising: a secondplurality of local area network nodes; and third communication cablingconnecting said second plurality of local area network nodes to saidpower data combiner, said power data combiner being further operative toprovide power via said third communication cabling to at least one ofsaid second plurality of local area network nodes, said second currentlimiting circuitry being further operative to provide a current limitfor each of said powered second plurality of local area network nodes.48. A local area network according to claim 44, wherein said power datacombiner is integrated within one of a hub and a switch.
 49. A localarea network comprising: a plurality of first local area network nodes;a first switch assembly; a second switch assembly; first communicationcabling connecting said plurality of first local area network nodes tosaid first switch assembly for providing data communication; and secondcommunication cabling connecting said first switch assembly to saidsecond switch assembly, said second switch assembly being operative toprovide at least some power via said second communication cabling tosaid first switch assembly; said first switch assembly comprising: firstline interface circuitry coupling at least some of said power providedby said second switch assembly into said first communication cablingsubstantially without interfering with data communication; and firstcurrent limiting circuitry connected to said line interface circuitryand controlling current delivered by said line interface circuitry intosaid first communication cabling, wherein said first switch assembly isoperative to provide at least some power to at least some of saidplurality of first local area network nodes via said first communicationcabling, said first current limiting circuitry being operative toprovide a current limit level for each of said first local area networknodes being provided power via said first communication cabling.
 50. Alocal area network according to claim 49, further comprising: a secondplurality of local area network nodes; and third communication cablingconnecting said second plurality of local area network nodes to saidsecond switch assembly, said second switch assembly being furtheroperative to provide power via said third communication cabling to atleast one of said second plurality of local area network nodes.
 51. Alocal area network according to claim 49, wherein said second switchassembly comprises: second line interface circuitry coupling power intosaid second communication cabling substantially without interfering withdata communication; and second current limiting circuitry connected tosaid second line interface circuitry and controlling current deliveredby said second line interface circuitry into said second communicationcabling, said second current limiting circuitry being operative toprovide a current limit for said power provided to said first switchassembly.
 52. A local area network according to claim 51, furthercomprising: a second plurality of local area network nodes; and thirdcommunication cabling connecting said second plurality of local areanetwork nodes to said second switch assembly, said second switchassembly being further operative to provide power via said thirdcommunication cabling to at least one of said second plurality of localarea network nodes, said second current limiting circuitry being furtheroperative to provide a current limit for each of said second pluralityof local area network nodes being provided power via said thirdcommunication cabling.
 53. A method of powering a switch, the methodcomprising: receiving a first plurality of data signals; receiving a lowfrequency power signal; combining said received plurality of datasignals and said received low frequency power signal into a plurality offirst combined power/data signals, said power substantially notinterfering with said data signal, said plurality of first combinedpower/data signals being transmittable over data communication cablingto a first plurality of nodes, at least one of said first plurality ofnodes comprising a switch assembly; limiting current to a current limitlevel for each of said plurality of first combined power/data signals;transmitting at least one of said first combined power/data signals overcommunication cabling to said switch assembly; splitting said at leastone of said first combined power/data signal into separate power anddata components at said switch assembly; and powering said switchassembly with said power component.
 54. A method according to claim 53,further comprising; switching said data component to a second pluralityof nodes; combining said power component with said switched datacomponent to provide at least one second combined power data signal,transmitting said second combined power data signal to at least one ofsaid second plurality of nodes.
 55. A powered switch comprising: meansfor receiving a combined power data signal at an input; a splitteroperable to split said received combined power data signal into separatepower and data components; a power/data combiner operable to combinesaid power component into a plurality of combined power data outputs,each of said plurality of combined power data outputs having anassociated maximum current threshold level.
 56. A powered switchaccording to claim 55, wherein each of said plurality of combined powerdata outputs are transmittable over communication cabling.
 57. A poweredswitch according to claim 55, wherein said maximum current thresholdlevel is one of fixed and controllable for each of said combined powerdata outputs.
 58. A powered switch according to claim 55, wherein saidpower data combiner comprises: line interface circuitry coupling atleast some of said power component into said plurality of combined powerdata outputs substantially without interfering with data communication;and current limiting circuitry connected to said line interfacecircuitry and controlling current delivered by said line interfacecircuitry into said plurality of combined power data outputs.
 59. Apowered switch according to claim 58, wherein said current limitingcircuitry is operative to provide a current limit level for each of saidplurality of combined power data outputs.
 60. A method comprising:receiving a combined power data signal at an input; splitting saidreceived combined power data signal into separate power and datacomponents; combining said power component into a plurality of combinedpower data outputs; and limiting the current of each of said pluralityof combined power data outputs to an associated maximum currentthreshold level.